Jawabanmu

2016-11-17T01:23:12+07:00
Diketahui:
2 cos (x + π/4) = cos (x - π/4)

Ditanya:
tan x

Penyelesaian:

⇔ 2 cos (x + π/4) = cos (x - π/4)

⇔ 2.[cos x.cos π/4 - sin x. sin π/4] = [cos x.cos π/4 + sin x. sin π/4]

⇔ 2.[½√2 cos x - ½√2 sin x] = [½√2 cos x + ½√2 sin x]

⇔ 2 x ½√2 [cos x - sin x] = ½√2 [cos x + sin x]......dibagi oleh ½√2

⇔ 2 cos x - 2 sin x = cos x + sin x

⇔ cos x = 3 sin x

⇔ sin x / cos x = 1/3

∴ tan x = 1/3
1 5 1